For security reasons, there is only one option.  The unit needs to be sent to Philips for a factory reset.  All US customers can send their devices to:

Steve Kemble
Philips Speech Processing

13560 Morris Road
Suite 1400
Alpharetta, GA 30004

Please use a shipping method that provides tracking information.

Verification Source:  In-house testing

Test Date: 3.19.12